Multi-phase circuit breaker having spring mounting for interlocking tie bar

ABSTRACT

A multipole molded case circuit breaker having a single springpowered operating mechanism for the contacts of all poles is constructed with the contact connecting tie bar seated in bearing recesses of the mechanism frame so that this tie bar is pivoted about a longitudinal axis extending through the tie bar.

United States Patent [191 Michetti Sept. 23, 1975 MULTI-PIIASE CIRCUIT BREAKER HAVING SPRING MOUNTING FOR INTERLOCKING TIE BAR [75] Inventor: Anthony B. Michetti, Warminster,

[73] Assignee: l-T-E Imperial Corporation, Spring House, Pa.

[22] Filed: May 13, 1974 [21] Appl. N0.: 469,374

[52] U.S. Cl 200/50 C; 200/244; 200/250 [51] Int. Cl. H01H 9/20 [58] Field of Search 200/50 C, 244, 250, 247,

200/282, DIG. 6; 335/127-131, 159-161, 196, 197, 202; 337/43, 338, 339

[56] References Cited UNITED STATES PATENTS Weber 335/127 3,056,008 9/1962 Schwartz 335/127 3,239,638 3/1966 Gryctko et a1 200/244 3,486,150 12/1969 Clarke 337/43 Primary ExaminerJames R. Scott Attorney, Agent, or FirmOstrolenk, Faber, Gerb & Soffen [57] ABSTRACT A multipole molded case circuit breaker having a single spring-powered operating mechanism for the contacts of all poles is constructed with the contact connecting tie bar seated in bearing recesses of the mechanism frame so that this tie bar is pivoted about a longitudinal axis extending through the tie bar.

7 Claims, 4 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of 3 3,908,104

US Patent Sept. 23,1975 Sheet 2 of3 3,908,104

US Patent Sept. 23,1975 Sheet 3 of3 3,908,164 U MULTl-PIIASE CIRCUIT BREAKER'HAVING SPRING MOUNTING FOR INTERLOCKING TIE This invention relates generally to rn'ultipole molded case circuit breakers, and relates more particularly to circuit breakers of-this" type having a novelmounting for the tie bar that is mechanically connected to the movable contacts of all poles for simultaneous operation. 1 i I Multipole molded case circuit-breakers of moderate current ratings vare usually constructed with-a single springpowered mechanism connected directly to the movable contact of one pole. A tie bar connects the movable contacts of all poles together so that the operating mechanism opens and closes all poles simultaneously..U.S. Pat. No. 3,239,638, issued Mar. 8, 1966, to C. E. Gryctko et.al., for Circuit Breaker Device In-. cluding Stop Means For Limiting Contact Arm Movement, illustrates this type of multipole circuit breaker constructed with a contact connecting tie bar that is pivoted about a longitudinal axis extending through the tie bar. This axis is defined by pivot pins extending into varying apertures at opposite ends of the tie bar. .The pivot pins are mounted to individual brackets screwed. to the base portioniof the circuit breaker housing after the contact operating mechanism is secured to the base. During assembly great pains must be taken to as sure that the brackets having the pivotpin's areaccurately placed so that the pivot pins are alignment and the tie bar is not askew.

In order to simplify assembly of the general type of circuit breaker described in the aforesaid U.S. Pat. No. 3,239,638, the instant invention provides a construction in which the contact operating mechanism frame is provided with pivot bearings upon which the contact tie bar is seated and wherein the tie bar pivots about a longitudinal axis extending through the tie bar. This is a less expensive construction and provides a more rigid support for the tie bar. Elimination of the outboard bearings makes the contact operating mechanism and the movable contacts a complete unit that is easily mounted in the circuit breaker housing in proper alignment with cooperating elements such as the stationary contacts and arc chutes. All in all, circuit breaker fabrication is speeded up and the circuit breaker parts are less costly than in similar prior art circuit breakers.

Accordingly, a primary object of the instant invention is to provide a novel construction for a multipole molded case circuit breaker which is less costly to produce than similar prior art circuit breakers.

Another object is to provide a circuit breaker of this type having a construction which facilitates mounting of the contact operating mechanism in the circuit breaker housing.

Still another object is to provide a circuit breaker of this type in which a more rigid support is provided for the tie bar extending between the movable contacts of all poles.

A further object is to provide a circuit breaker of this type having a Contact connecting tie bar that is seated on bearing formations formed in the frame of the operating mechanism so as to be pivoted about a longitudinal axis extending through the tie bar.

These objects as well as other objects of this invention shall become readily apparent after reading the following description of the accompanying drawings in which:

FIG. 1 is a plan view of a three-pole molded case circuit breaker constructedin accordance with teachings of the instant invention, with a major portion of the housing cover broken away to reveal internal elements.

FIG. 2 is a cross-section-taken through line 22 of FIG. 1, looking in'the direction of arrows 22.

FIG. 3 is an end view of the operating mechanism frame showing the movable contact arm tie bar mountedto the frame.

FIG. 4 is aside elevation of the operating mechanism frame looking in the direction of arrows 4-4 of FIG. 3, with selected elements shown mounted to the frame.

Now referring to the figures. Multipole molded case circuit breaker 10 shown in FIGS. 1 and 2 is of the general type described in U.S. Pat. No. 3,239,638, issued Mar. 8, 1966, to C. E. Gryctko et al. for a Circuit Breaker Device Including StopMeans For Limiting Contact Ai'rn Movement. The electricalelements of circuit breaker 10 are operatively positioned within parallel elongated compartments of base 11 separated by partitions 11a, 11b. Removable cover 12 is joined to base 11 along line 13. The current path for each pole of circuit breaker 10 consists'of plug-in line terminal 24,'extension 24a, strap 14, movable contact 15, stationary contact 16, movable contact arm 17, flexible conducting braid l8,' terminal piece 19, bimetal heater 20, magnetic trip winding 21, and plug-in load terminal 22. As is well known to 'the art, coil 21 and bimetal heater 20 are elements of automatic trip unit 25.

Contact operating mechanism 23, disposed within the center compartment of base 11, is of the spring powered overcenter toggle type'including operating springs 49 connected between manual operating handle 51 and toggle knee 52. Inverted U-shaped extension 71 secured to the bottom of handle 51 straddles mechanism frame and is pivoted thereto on outward projections 72. Knee 52 connects upper and lower toggle links 53, 54, respectively. The upper end of upper toggle link 53 is mounted to releasable cradle 55 at pivot 56, and the lower end of lower link 54 is connected at pivot pin 47 to contact arm support 30. Pin 35 pivotally mounts contact arm 17 to support 30. Spring assembly 42, backed by plate 44, is mounted to the bottom of support 30 and engages the end of contact arm 30 remote from movable contact 16 to provide a contact biasing force when contacts 15, 16 are engaged.

Transverse insulating tie bar 33, of rectangular crosssection, extends through aligned rectangular openings in support 30, being held therein by clamp-plate 32 so that the contact arm supports 30 of all three poles are mounted to tie bar 33 for simultaneous operation by the single contact operating mechanism 23.

Mechanism frame 60 is generally U-shaped including spaced upwardly extending arm 61, 62 connected by web 63. The latter includes threaded apertures which receive screws 64 that secure mechanism 23 in operative position within housing 11. Each of the frame arms 61, 62 is provided with a bearing slot 65, open at the left and closed at the right, as viewed in FIG. 4. At spaced points intermediate the ends thereof, tie bar 33 is undercut to provide spaced circular bearing formations 66, 66 that are received within bearing slots 65 and rest against the closed ends thereof, so that tie bar 33 is mounted to pivot about its longitudinal axis, being supported directly on mechanism frame 60. Spring retainers 70, 70, having offset ends extending through frame apertures 68, 69, extend around the left portion of tie bar bearing sections 66, 66 as viewed in FIG. 4, to maintain bearing sections 66, 66 within bearing slots 65, 65.

Thus it is seen that the instant invention provides a novel mounting for the contact arm tie bar of a multipole circuit breaker to facilitate assembly and reduce costs.

Although there have been described preferred cmbodiments of this novel invention, many variations and modifications will now be apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein, but only the appended claims.

The embodiments of the invention in which an enclusive privilege or property is claimed are defined as follows:-

l. A multipole circuit breaker including a housing having internal partitions defining parallel compartments, one for each pole of said circuit breaker; within each of said compartments, contact means including a stationary contact and a movable contact engageable with and disengageable from said stationary contact, a movable contact arm to which said movable contact is mounted, and a carrier to which said arm is mounted, tie bar means extending across said compartments and rigidly connected to said carriers for simultaneous movement thereof as said rod is pivoted about a longitudinal axis extending therethrough; a spring powered operating mechanism connected to a first of said carriers for simultaneously operating the contact means of all poles of said circuit breaker into and out of engagement; said operating mechanism including a stationary frame having aligned spaced bearing formations; said rod being seated on said bearing formations whereby said rod is mounted for pivotal movement about said longitudinal axis; and spring clip means retaining said rod seated on said bearing formations.

2. A multipole circuit breaker as set forth in claim 1 in which the rod is provided with longitudinally spaced grooves into which boundary portions of the bearing formations extend.

3. A multipole circuit breaker as set forth in claim 1 in which said spring powered operating mechanism is mounted in a first of said parallel compartments; said circuit breaker also including a second and a third of said parallel compartments positioned on opposite sides of said first compartment.

4. A multipole circuit breaker as set forth in claim 3 in which, in each of said compartments, the movable contact arm is pivotally mounted to the carrier.

5. A multipole circuit breaker as set forth in claim 4 in which the rod is provided with longitudinally spaced grooves into which boundary portions of the bearing formations extend.

6. A multipole circuit breaker as set forth in claim 5 in which each of the bearing formations constitutes a boundary portion of a slot in said frame, each of said slots having an open end through which said rod is entered for seating on said bearing formations.

7. A multipole circuit breaker as set forth in claim 1 in which each of the bearing formations constitutes a boundary portion of a slot in said frame, each of said slots having an open end through which said rod is entered for seating on said bearing formations. 

1. A multipole circuit breaker including a housing having internal partitions defining parallel compartments, one for each pole of said circuit breaker; within each of said compartments, contact means including a stationary contact and a movable contact engageable with and disengageable from said stationary contact, a movable contact arm to which said movable contact is mounted, and a carrier to which said arm is mounted, tie bar means extending across said compartments and rigidly connected to said carriers for simultaneous movement thereof as said rod is pivoted about a longitudinal axis extending therethrough; a spring powered operating mechanism connected to a first of said carriers for simultaneously operating the contact means of all poles of said circuit breaker into and out of engagement; said operating mechanism including a stationary frame having aligned spaced bearing formations; said rod being seated on said bearing formations whereby said rod is mounted for pivotal movement about said longitudinal axis; and spring clip means retaining said rod seated on said bearing formations.
 2. A multipole circuit breaker as set forth in claim 1 in which the rod is provided with longitudinally spaced grooves into which boundary portions of the bearing formations extend.
 3. A multipole circuit breaker as set forth in claim 1 in which said spring powered operating mechanism is mounted in a first of said parallel compartments; said circuit breaker also including a second and a third of said parallel compartments positioned on opposite sides of said first compartment.
 4. A multipole circuit breaker as set forth in claim 3 in which, in each of said compartments, the movable contact arm is pivotally mounted to the carrier.
 5. A multipole circuit breaker as set forth in claim 4 in which the rod is provided with longitudinally spaced grooves into which boundary portions of the bearing formations extend.
 6. A multipole circuit breaker as set forth in claim 5 in which each of the bearing formations constitutes a boundary portion of a slot in said frame, each of said slots having an open end through which said rod is entered for seating on said bearing formations.
 7. A multipole circuit breaker as set forth in claim 1 in which each of the bearing formations constitutes a boundary portion of a slot in said frame, each of said slots having an open end through which said rod is entered for seating on said bearing formations. 